• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1230-1232
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• 2000

To reduce harmonics in the AC line and achieve a unit power factor, A 4 paralled single phase PWM AC/DC converter has been proposed. In this paper, the coupling components are derived analytically from PWM converter input transformer model and control scheme to solve this problem is proposed. Unit power factor was obtained and the AC-side current harmonics were reduced. Simulation results show the usefulness of the proposed method and applicability to PWM converter in auxiliary block of high speed train.

• Proceedings of the Safety Management and Science Conference
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• 1999.11a
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• pp.345-354
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• 1999

A new type of capacitor named "Super Capacitor" has been developed, in which the properties of electric double layer formed at the interface of activated carbon electrode- liquid organic electrolyte is applied. This capacitor is small In size, light in weight, wide In temperature range(-25~$70^{\circ}C$), large in charge-discharge capability and good in voltage preservation. And this super capacitor is applied as a power back-up for electricity failure in volatile memory devices etc., a power source for a short time and a power source for operating actuators. At present the development of high power back-up types of the capacitor system and improvement of their characteristics are being actively conducted in order to find wider applications.lications.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.4
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• pp.282-290
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• 2000

In this paper, the charge control with the input voltage feedback is proposed for the input series-output series-output parallel connected converter configuration for the high speed train power system application. This control scheme accomplishes the output current sharing for the output-parallel connected modules as well as the input voltage sharing for the input series connected modules for all operating conditions including the transients. It also offers the robustness for the input voltage sharing control according to the component value mismatches among the modules. And this configuration enables the usage of MOSFET for a high voltage system allowing a higher switching frequency for lighter system weight and smaller size. The performance of the proposed scheme is verified through the experimental results.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.146-149
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• 2008

최근 대기전력저감기능을 갖는 PWM IC를 적용한 플라이백 컨버터는 대기전력 모드 시 Burst 스위칭 동작에 의해 소모 전력을 최소화 할 수 있지만 경 부하 및 대기전력모드 시 변압기를 통해 흐르는 큰 여자전류에 의해 여전히 낮은 효율특성을 가지는 문제점이 있었다. 본 논문에서는 경 부하 및 대기전력모드 동작 시 변압기에 흐르는 여자전류를 최소화함으로 효율을 개선한 회로를 제안하였으며 50인치 PDP TV PSU (Power Supply Unit)에 있어서 대기전력 및 보조전원으로 사용된 74W 플라이백 컨버터에 적용하여 비교 검토하여 보았다.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.238-240
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• 2008

다양한 기능을 동시에 구현하는 최근의 전자제품을 위한 전력 시스템은 다양한 종류의 전원을 구비해야 하며, 고효율 저가격 특성이 필수적이다. 이를 위해 본 논문은 단일 변압기를 이용한 중 용량급의 고효율 저가격형 다중출력 LLC 공진형 컨버터를 제안한다. 제안된 컨버터는 단일 변압기를 이용하고, 요구되는 출력 당 추가된 1 개의 보조 스위치만으로 구현되므로 저가격화에 유리하다. 또한 제안된 회로의 모든 전력 스위치들은 ZVS 및 ZCS가 가능하므로 스위칭 손실을 최소화 할 수 있다. 최종적으로 제안된 컨버터 및 전원시스템의 우수성과 이론적 분석의 타당성 검증을 위해 42" FHD급 PDP용 전원회로를 위한 시작품을 제작하여 고찰된 실험결과를 제시한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.540-548
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• 2007

The parer proposes a power factor correction high efficiency PWM single-phase rectifier. Its good characteristics such as simple PWM control, low switch stress, and low VAR rating of commutation circuits make the proposed rectifier very suitable for various unidirectional power applications. In addition, the proposed rectifier consists of three boost-converter-type IGBT modules with the switching devices located at the bottom leg of the rectifier scheme, which also enables the use of the same power supply in both control and gate driver, thus resulting in simple control and power circuit structure. The detailed principle of operation and experimental results are also included. In particular, the design guide line is also suggested to make the circuit design of the proposed rectifier easy and fast.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.5
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• pp.73-79
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• 2008

This paper presents a simple electronic starter for single phase induction motor (SPIM). It replaces the centrifugal switch in the auxiliary winding circuit of the capacitor start type SPIM. The electronic starter observes the auxiliary winding voltage, and disconnects the auxiliary winding when the motor gets close to its rated speed. Because of its possibly fluttering contacts of the centrifugal switch which mounted on the conventional SPIM, the reliability of SPIM can be reduced. Developed new electronic starter has no mechanical contacts. Therefore, the reliability and the performance of SPIM can be improved. The operational principle of the proposed electronic starter is explained, and illustrated with experimental results.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.5
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• pp.11-116
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• 2000

A topology decreased switching loss and voltage stress by zero voltage switching is presented in this paper. Generally, Switching mode converting productes voltage stress and power losses due to excessive voltage and current. which affect to performance of power supply and reduce overall efficiency of equipments. Virtually, In flyback converter, transient peak voltage and current at switcher are generated by parasitic elements. To solve these problems, present ZVS flyback converter topology applied a auxiliary circuit. Incorporation of auxiliary circuit into a conventional flyback topology serves to reduce power losses and to minimize switching voltage stress. Snubber capacitor in auxiliary circuit serves ZVS state by control voltage variable time at turn on and off of main switch, then reduces voltage stress and power losses. The proposed converter has lossless switching in variable load condition with wide range. A detailed analysis of the circuit is presented and the operation procedure is illustrated. A (50W 100kHz prototype) ZVS flyback converter using a auxiliary circuit is built which shows an efficiency improvement as compared to a conventional hard switching flyback converter.

• Nuclear industry
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• no.6
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• pp.20-22
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• 1979

본문은, 일본의 통산성${\cdot}$에너지청이 4월 24일 일본의 원발20기에 대해서 행한 안전총점검의 중간보고를 요약한 것이다. 여기서, 보수관리상황을 점검한 주요설비는 다음과 같다. (1) 보조급수계 (2) 가압기방출 Valve (3) 비상용노심냉각장치 1) 고압주입계 2) 축압 Tank 3) 저압주입계 4) 격납용기내부 Spray계 5) 격납용기격리변 6) 비상용전원 등이며 주로 기동전 확인과 일상점검에 중점을 두었던 것이다.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.190-193
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• 2003

This paper Proposes 40 [KVA] rated SIV(Static Inverter) system for Light Rail Transit. The SIV Provide power of a fluorescent light in the car, Air-conditioner. and other equipments. To control output voltage it is used voltage control loop for constant voltage control and simultaneously used current control loop for instantaneous control at load changing. The Performance of SIV system will be verified by experimental results.